Here, Vn is the voltage of nth harmonic and V1 is the voltage of the fundamental signal. Voltage THD – same as THDi, total harmonic-distortion of voltage is denoted by THDv. Here, In is the RMS current for the nth harmonic signal and I1 is the RMS value of the fundamental signal. THD can be defined as the ratio between RMS values of all harmonic signals to the RMS value of the fundamental signal frequency.Ĭurrent THD – As per the above statement total distortion for current is indicated by THDi current-THDi Total harmonic distortion (THD) is the most useful technique to find the total harmonic-distortion for the current signal and total harmonic distortion for voltage signals. We can analyze these distortions by this value. Harmonic Distortion Analyzerįinding the harmonic distortion factor is most important for any circuit.
Because of the harmonic-distortions circuit gets heat and output not equal to the input. This also leads to the development of the harmonics in the output. And the components which are using in the circuit also show the nonlinearity characteristics. This leads to distortions will develop in the output signal. Nonlinear load changes the impedance with the applied input voltage. The main reasons for the harmonic-distortions are the nonlinear load and nonlinearity characteristics of the electronic components.
By this total harmonic-distortion measurement method, we can know the input and output voltages and input and output power.
If we analyze the distortions with total harmonic distortion measurement technique we can know the value of the total harmonic distortion (THD), total harmonic distortion plus noise (THDN), signal to noise and distortion (SINAD), signal to noise ratio (SNR) and nth harmonic value with respect to the fundamental frequency. Because of this, the reference signal may appear in the output at different frequency points. When the input signal is applied to the circuit, due to nonlinear characteristics of the components the distortion may develop in the output signal. In this type, a single frequency sinusoidal signal is applied to the circuit and its output with distortion to be measured and analyzed. The analysis of this distortion is a unique type of analysis. If the signal doesn’t have an equal time period of positive cycle and negative cycle, then such a signal is called asymmetrical signal and even harmonics may appear (multiplies 2nd, 4th, etc of the fundamental frequency) and DC components also may appear in the asymmetrical signals. If the signal having an equal time period of positive cycle and negative cycle, then such a signal is called symmetrical signal & odd harmonics may appear (multiplies 3rd, 5th, etc of the fundamental frequency).
Below two figures indicate the input signal & the distorted output when input is applied to any circuit. Theoretically, the signal includes infinite harmonics.
Here, signal X is the reference signal & the signal is showing on CRO have frequencies like 2f, 3f, 4f and so on. When the signal X is displayed on the CRO then the signal X will appear to repeat for every f Hz. For example, X is an input AC signal which has the frequency f Hz. In another way, it can be defined as the ratio between the frequency of the signal and the frequency of the reference signal. Here, harmonic is a type of signal whose frequency is an integral multiple of the reference signal. We can understand the word harmonic like the integer which multiplies fundamental frequencies is known as “Harmonics”.